Centrifugal compressor with recirculation passage

A centrifugal compressor comprising:

• a housing defining an inlet chamber and comprising first and second openings that define a recirculation passage in fluid communication with the inlet chamber;
• an impeller within the housing and rotatable about a longitudinal axis to draw fluid into the inlet chamber, the first and second openings at different axial locations along the longitudinal axis;
• a plurality of inlet guide vanes that are rotatable and situated in the inlet chamber;
• a first ring that includes a cam member;
• a second ring that includes a cam surface, wherein the second ring is separate from the first ring, and rotation of the second ring about the longitudinal axis translates the cam member along the cam surface and provides axial movement of the first ring;
• and
• a controller configured to rotate the second ring and thereby move the first ring along the longitudinal axis between a first position and a second position when rotating the inlet guide vanes, wherein the first ring obstructs at least one of the first and second openings more in the second position than in the first position.